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How Does a Wood Burner Work? A Complete Guide to Wood Burning Stoves and Fireplaces

Wood burning stoves and fireplaces have seen a resurgence in popularity in recent years as more people look for alternative and sustainable ways to heat their homes. But how exactly does a wood burner work to provide heat and ambiance to a living space?

In this comprehensive guide, we’ll explore the inner workings of wood burning stoves and fireplaces, the different types available, key components, how to operate them efficiently, maintenance tips, and frequently asked questions about wood burners. Whether you’re considering installing a new wood stove or just want to better understand how your existing fireplace works, read on to learn everything you need to know.

What is a Wood Burner?

A wood burner, also known as a wood stove or wood burning fireplace insert, is an enclosed, metal firebox that burns wood fuel for heat. Wood burners are designed to be installed in a home’s existing masonry fireplace (with a fireplace insert) or placed independently as a standalone stove.

Compared to an open fireplace, a wood burner uses less wood fuel, produces more heat from the fire, and releases far fewer emissions into the air. The key difference is that a wood stove contains the fire in a closed space, regulating air flow and maximizing heating efficiency. Fireplace inserts do the same while allowing you to keep the look and feel of your existing fireplace.

Inside the firebox, there are several components that work together to keep the fire burning cleanly and direct heat into the room:

  • An adjustable air inlet regulates oxygen flow into the firebox, which controls the intensity of the fire. This allows heat output to be adjusted.
  • Baffles guide airflow and smoke inside the firebox for increased efficiency.
  • A flue channels smoke and exhaust from the fire up and outside through the chimney.
  • Fans in some models help circulate warm air from the firebox into the room.

Together, these components allow modern wood stoves to burn fuel efficiently, producing more heat energy from less wood compared to conventional open fireplaces.

How Does a Wood Burning Stove Work?

A wood stove works by burning wood inside the firebox, heating up the internal stove surfaces which then radiate heat outward into the room. The fire requires oxygen to burn, which enters through adjustable air inlets on the stove. Once lit, the amount of available oxygen determines the intensity and heat output of the fire.

Step 1: Loading the Firebox

To begin, place several pieces of kindling, small dry twigs, and newspaper tightly in the bottom of the firebox. Then stack small split logs crisscrossed over the kindling, leaving air gaps in between.

Step 2: Lighting the Fire

Light the newspaper or a firelighter cube underneath the kindling to begin the ignition. Leave the air inlet open fully at first to feed the fire with plenty of oxygen. Slowly add larger pieces of wood on top as the fire starts burning.

Step 3: Regulating Air Flow

Once the fire is established, use the air inlet controls to regulate oxygen intake. This will control the intensity of the burn. Leaving the air control fully open will make the fire burn hotter and faster, while closing it down will lower the temperature.

Step 4: Adding Fuel

As the fire dies down, add more wood in a crisscross pattern, being careful not to smother the existing coals. It’s best to use moderately-sized logs to sustain an even, efficient burn. Make sure to leave air gaps between the logs.

Step 5: Circulating Warm Air

As the fire burns, internal chambers, baffles, and fans (in models with blowers) help circulate the warm air and distribute heat to the metal stove surfaces. The stove radiates this warmth outward into the living space.

Step 6: Managing the Flue

Ensure the flue is open while a fire is burning so that smoke can escape up the chimney. Close the flue when the fire is completely out or to retain heat when the fire has died down. The flue helps regulate oxygen flow as well.

By properly managing the airflow, fuel load, and flue, a wood stove’s heat output can be precisely controlled. Getting the hang of starting and maintaining a good fire will take some practice, but once mastered, wood stoves provide cozy radiant warmth.

How Does a Wood Burning Fireplace Insert Work?

A fireplace insert works on a similar principle as a wood stove but is installed inside an existing masonry fireplace. Like a wood stove, it burns wood contained in a closed firebox to increase heating efficiency and reduce emissions. In addition to the standard components of a stove, an insert has a few other parts that allow it to operate safely inside a fireplace.

Surround Panel: Seals off the existing masonry fireplace opening and channels heat from the insert into the room. Usually steel but can be cast iron.

Insert Body: The metal firebox that contains the fire and houses internal chambers and baffles.

Existing Masonry Firebox: Acts as a barrier to prevent heat loss and protect surrounding materials. No longer used for active burning.

Flue Liner: Runs smoke and exhaust up through the chimney. usually stainless steel or aluminum.

Fireplace inserts work as follows:

  1. A fire is lit inside the insert’s firebox while cool air enters below.
  2. Internal baffles and chambers route airflow and smoke from the fire up through the flue liner and out the chimney.
  3. The insert body absorbs heat from the fire and radiates it into the room through the surround panel. The masonry firebox also absorbs and re-radiates heat.
  4. Replacing the old damper with a flue liner reduces heat loss up the chimney when the insert is not in use.
  5. The existing brick fireplace limits heat transfer to surrounding walls, protecting the structure.

So while the contained fire burns much more efficiently than an open fireplace, the insert still allows you to enjoy the ambiance and heating ability of your existing indoor fireplace.

Types of Wood Burning Stoves and Inserts

Now that we’ve covered the general principles of how wood burners work, let’s look at the common types of stoves and inserts you can choose from:

Standard Wood Stove

The classic wood stove with firebox, air controls, baffles, and flue collar. Available in many styles. Freestanding away from a fireplace. Less efficiency than other types but simple operation and lower cost.

Catalytic Combustor Stove

Uses a catalytic combustor—usually a honeycomb-like component coated with a noble metal—above the firebox to further burn uncombusted gases, increasing heat output. More efficient and lower emissions but the combustor requires replacement over time.

Non-Catalytic Stove

Engineered firebox design that promotes secondary combustion of gases above the fire without a combustor. Good efficiency without the combustor maintenance requirement. Baffles and reburn tubes generate secondary combustion.

Pellet Stove

Burns compressed wood pellet fuel that is fed into the firebox via an auger automatically controlled by the stove’s thermostat. Convenient to operate and high efficiency. Requires access to wood pellets.

Gas Fireplace Insert

Burns natural gas or propane for fireplace inserts instead of wood. No need to stock and load firewood. Heat output can be precisely adjusted. Requires access to a gas line.

Electric Fireplace Insert

Uses electric heating elements instead of combustion. Zero emissions and no chimney required but higher operating costs compared to wood. Maintenance-free operation.

Each variety has pros and cons in terms of efficiency, cost, maintenance, and operation. Consider your needs, preferences, and existing fireplace setup when deciding which is best for you.

Key Parts of a Wood Stove

While specific wood stove models can vary, most incorporate the following key components in their design:

  • Firebox – Metal enclosure that contains the fire. Usually steel plate or cast iron with heat resistant paint.
  • Air Inlets – Adjustable vents that control air flow into the firebox, regulating burn intensity.
  • Glass Viewing Door – Ceramic glass window offering a view of the fire while containing sparks. Can be air-washed to reduce soot buildup.
  • Baffles – Steel internal channels that route smoke and airflow for improved efficiency and emissions.
  • Flue Collar – Opening that attaches stove to chimney or flue liner through which exhaust flows.
  • Legs or Pedestal – Supports the stove above the floor for safety. Allows air circulation.
  • Surround Panel – Decorative and functional façade around insert that radiates heat into the room.
  • Insulated Lined Body – Absorbs heat while protecting outer surfaces from excess heat. Makes outer jacket cool to the touch.
  • Convection Chambers – Interior spaces that catch heat and circulate air to improve heat transfer to the room.
  • Catalytic Combustor – Platinum honeycomb mesh that ignites unburnt gasses, increasing efficiency (in catalytic models).

How to Operate a Wood Burning Stove

Learning to properly operate your wood stove or insert will ensure optimal performance and safety. Here are some key tips:

  • Carefully read your owner’s manual to understand recommended operation procedures.
  • Always keep the flue and chimney clear of obstructions before lighting a fire.
  • Open the air inlet fully when first lighting or rekindling the fire to establish a good burn.
  • Once the fire has ignited, adjust the air control to regulate temperature. Don’t smother the fire.
  • Use moderately sized logs and refuel on a bed of hot coals to maintain an even burn.
  • Be present anytime a fire is burning and use fire screens and tools. Never over-fire the stove.
  • Allow the stove to cool completely before handling or conducting maintenance.
  • Have your chimney professionally cleaned annually to remove creosote deposits.

It’s also wise to invest in an inexpensive stove-top thermometer to monitor your burn temperatures and stay within the optimal operating range. This helps maximize efficiency and safety.

Maintaining Your Wood Burner

Proper maintenance will keep your wood stove or insert working safely and efficiently for years to come. Here are some top maintenance tips:

Daily:

  • Remove ash and soot which can build up quickly, impeding airflow.
  • Clean glass viewing panes with stove glass cleaner or vinegar.
  • Check door seals for any air leaks which reduce efficiency.

Weekly:

  • Vacuum ash from hidden crevices and hard to reach areas in the firebox.
  • If using a catalytic combustor, visually check it for damage or degradation.

Yearly:

  • Inspect the flue liner and chimney for any damage or blockages.
  • Have the firebox, internal chambers, and flue professionally cleaned.
  • Replace any damaged components like bricks or baffles.

As Needed:

  • Replace gaskets around doors and glass if they become loose or compressed.
  • Repaint external surfaces with high temperature paint to renew protection.
  • Replace a damaged catalytic combustor.

A clean burning, hot fire is key to reducing work. Also be sure to only burn dry, seasoned firewood. Well maintained stoves and inserts can last for many decades.

Frequently Asked Questions About Wood Burners

If you’re in the market for a wood stove, fireplace insert, or recently installed one in your home, chances are you have plenty of questions. Here we answer some of the most common queries about wood burners:

How much wood will a stove or insert burn?

  • Wood consumption depends on the heater’s BTU rating and your desired heat level. Typical ranges are between 1/2 cord to 5 full cords per season for smaller homes. Hard, dense woods like oak burn slower while soft woods burn faster but hotter.

What is the best wood for burning?

  • Seasoned hardwoods that have been split and air-dried for 12+ months, like oak, hickory, or maple make the best fuel. Softwoods burn fast and resinous woods leave more creosote. Avoid wet wood which burns inefficiently.

How often will I need to refill the firebox?

  • This varies on stove design and wood type, but expect to add more logs every 1 – 3 hours. Smaller loads of dense hardwood burn longest between refills.

Can a wood insert be installed in any masonry fireplace?

  • Generally yes, provided the existing fireplace is in good condition up to code, properly sized, has a suitable flue, and meets clearance requirements. Always have a professional assess suitability.

Do inserts or stoves require electricity?

  • Electricity may be required for a stove blower to circulate air. Inserts and stoves without blowers do not require power. Pellet stoves need electricity to power the pellet feed system.

What maintenance does a wood burner require?

  • Wood stoves need the ash cleared frequently, glass cleaned, seals checked, and annual professional cleaning/inspection. Catalytic stoves also require periodic combustor replacement.

How much heat can a wood burner provide?

  • Output ranges widely from 10,000 – 90,000 BTUs depending on the stove and your burning habits. A medium 50,000 BTU stove can warm 1,000+ sq ft. in a reasonably insulated home.

Are wood stoves safe?

  • Modern wood stoves and inserts are designed much safer than in the past. With proper operation, maintenance, and clearance to combustibles, they pose minimal risk. Still, ensure smoke and CO detectors are present.

Can I burn coal in a wood stove?

  • No. Wood stoves and inserts are only intended and approved for burning seasoned wood. Coal and other fuels can produce toxins, damage components, lead to unsafe operation. Burning anything other than wood also voids warranties.

If properly selected, installed, and maintained, a wood burning fireplace insert or freestanding stove can provide years of reliable, renewable heat. Following the guidelines in this guide will help ensure optimal performance and enjoyment of your wood burner.

Laura Kassovic

Laura Kassovic, a former engineer at Intel SOC, now dedicates her efforts to mentoring startups in the realms of Wearables and AI. As a co-founder of New Tech Brake, she spearheads a wireless sensing solution enterprise catering to diverse applications including product development, research, location tracking, and people monitoring, as well as asset and cargo supervision. The platform empowers developers to craft an array of innovations such as fitness trackers, temperature-monitored cargo systems, medical trial tools, smart running garments, or even straightforward transmission of unprocessed accelerometer data to cloud-based repositories.

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